Testing for the release of soluble mediators is customarily performed by collecting the supernatant of the cells which release the putative substance, and adding this substance to cultures of indicator cells, the growth of which can be measured by .sup.3 H-thymidine uptake. This procedure takes several days, and some short-lived mediators, such as prostaglandins, may not be measurable in this way, as they would deteriorate in the medium. Labile substances may be bioassayed in a one-step procedure, by plating the producer and the indicator cultures in chambers separated by a semipermeable membrane, such as the Marbrook chamber, through which the soluble substance can diffuse as it is produced. This chamber is described in greater detail in Marbrook, J., 1980, in Selected Methodsin Cellular Immunology, eds. B. B. Mishell and S. M. Shiigi (W. H. Freeman and Company, San Francisco) p.37. The drawback of this method is that some mediators may bind to the membrane, and that standard cell labelling and harvesting procedures cannot be used directly to assay the growth of the indicator culture.
In British patent No. 2,094,831 A, there is described a tray for identifying isolated microorganisms consisting of a plastic or glass tray body and a cover. Each cell in the tray has a barrier which is nearly vertical on one side and sloping on the other, the barrier being lower in height that the overall cell walls. In use, dried reagents are prepared in the wells of the small cells, bacterial suspension is poured into each of the adjoining cells, and the entire tray is inclined so that the cells for bacterial suspension are introduced over the barriers to inoculate the reagent cells.
European Patent No. 121,981, discloses a support for an immobilized cell composite. The support structure is a honeycombed monolith having inlet and outlet faces which allow liquid to flow through channels in the monolith to provide nutrients to the anchored cells.
Tolbert et al., U.S. Pat. No. 4,537,860, disclose an apparatus for maintaining animal cells in vitro in a substantially arrested state of proliferation with continuous secretion of cell product. The cells are retained in the reactor vessel chamber in a semirigid matrix having interstices for passage of fluid nutrient medium.
Lanier, U.S. Pat. No. 3,938,961 discloses a sample tray for storing fluid test specimens suitable for filling fluid dispensers. Isolated catch basins surround each test specimen reservoir so as to prevent commingling of test specimen fluids that may spill over the edge of the fluid receiving compartment, either during filling or while the specimen fluid is being withdrawn therefrom.